- Fix a memory leak in AI "payTheManaCost"

- Minor fixes in AI code
- Attempt at preventing the AI from interrupting itself while it's selecting targets. I don't know why this happens, and my fix didn't work. I believe it shouldn't be possible to interrupt when there is an active targetChooser, please let me know if this is an incorrect assumption.

projects/mtg/src/GameStateDuel.cpp

@@ -620,7 +620,7 @@ void GameStateDuel::Render()
           if (totalTestGames < 2.5 * totalAIDecks)
           {
                mFont->SetColor(ARGB(255,255,255,0));
-               sprintf(buf, "Results are not significant, you should let at least %i more games run", totalAIDecks * 2.5 - totalTestGames);
+               sprintf(buf, "Results are not significant, you should let at least %i more games run", (int)(totalAIDecks * 2.5) - totalTestGames);
                mFont->DrawString(buf,0,SCREEN_HEIGHT/2 - 20);
           }